New gun fires projectiles at seven times the speed of sound and works by creating an electromagnetic field between two conductive rails

Explosive test footage of a futuristic new weapon has been released by the US military, as they gear up to test it at sea for the first time.

The US Navy is to demonstrate the electromagnetic rail gun, which fires projectiles at seven times the speed of sound, on a high speed vessel from next year.

The weapon works by creating an electromagnetic field between two conductive rails, launching a projectile at supersonic speeds.

The high speeds involved mean they can use much cheaper ammunition, costing only $25,000 (£15,000) rather than a $1m (£600,000) missile - and still have a devastating effect on enemy ships and aircraft.